If you want to wear your Chivo shirt with pride, head to Melrose Park. When you stroll downtown Melrose Park, just off lake, you will feel transported straight to some sleepy town in Mexico (minus the hills). You will find a place called Birria 3 Morello that features the very underated cuisine of Guadalara. The carne en su jugo is especially good as is the namesake birria (with or without the soup).
As to vietamese sandwhiches, I only know of two places:bale and vin phat. Essentially, they bracket argyle streets. The easiest solution is to see which side of argyle you find yourself. Bale's staff speaks a bit more english. They also have a bunch of "snacks" displayed. Use your eyes as the english translations do not always work. The egg rolls are especially good, even cold. And on top of that, their crossants rock. My only quibble with Bale's sandwiches is that they put mayonaise on the sandwhiches unless otherwise specified.